In most land vehicles in use today, a drive train assembly is provided for transmitting rotational power from an output shaft of an transmission to an input shaft of an axle assembly so as to rotatably drive one or more wheels of the vehicle. To accomplish this, a typical vehicular drive train assembly includes a hollow cylindrical driveshaft tube. A first universal joint is connected between the output shaft of the transmission and a first end of the driveshaft tube, while a second universal joint is connected between a second end of the driveshaft tube and the input shaft of the axle assembly. The universal joints provide a rotational driving connection from the output shaft of the transmission through the driveshaft tube to the input shaft of the axle assembly, while accommodating a limited amount of angular misalignment between the rotational axes of these three shafts.
A typical universal joint includes a cross having a central body portion with four cylindrical trunnions extending outwardly therefrom. The trunnions are oriented in a single plane and extend at right angles relative to one another. A hollow cylindrical bearing cup having a cylindrical outside wall and a circular end wall is mounted on the end of each of the trunnions. A bearing structure, such as a plurality of needle bearings or roller bearings, is provided between the trunnion and the associated bearing cup to facilitate relative rotational movement therebetween. The bearing cups that are mounted on a first opposed pair of the trunnions can be connected to a first yoke secured to a first component of the drive train assembly, while the bearing cups mounted on a second opposed pair of the trunnions can be connected to a second yoke secured to a second component of the drive shaft assembly.
When the bearing cups are mounted on the associated trunnions, the circular end walls of the bearing cups are disposed adjacent to the axially outer ends of the trunnions and bearings. If the inner surfaces of these end walls directly contact the axially outer end surfaces of the trunnions during operation, friction caused by such direct contact can generate undesirable heat and wear. However, if the inner end surfaces of the bearing cups do not fit snugly against the axially outer end surfaces of the trunnions, relative axial movement between the bearing cups and the trunnions can cause imbalances and result in undesirable noise and vibrations. Thus, to address these situations, it is known to position a thrust washer between the inner end surface of the bearing cup and the axially outer end surface of the trunnion. A typical thrust washer is formed from a relatively low friction, wear resistant material, such as plastic, that can absorb the thrust loads that occur between the end of the trunnion and the bearing cap and take up any looseness therebetween.
A thrust washer can absorb some axial load and torque from the vehicle driveline such as that experienced under normal driving conditions. However, a typical Cardan universal joint is not equipped for handling high axial loads and torque. Under high thrust loads, the normal tolerance of a thrust washer will be exceeded, resulting in unacceptable vibrations in the vehicle driveline. In addition, excessive axial loads and torque may cause the ends of a typical cross to flex while placing unacceptable load and torque on the lug structures of the yoke. Thus, it would be desirable to provide an improved structure for a universal joint assembly that addresses these concerns.